N5315 Gastrointestinal Core Knowledge Objectives with Advanced Organizers

Gastrointestinal Core Concepts and Objectives with Advanced Organizers GI System Anatomy and Physiology Examine the anatomy and physiology of the GI system: 1. Differentiate between the organs which make up the upper gastrointestinal track and the lower gastrointestinal track. o The upper Gi track is made up of the mouth, esophagus, stomach, and the first part of the small intestine (duodenum) o The lower Gi track consist of the large intestine and the anus. 2. Explain the hepatoportal circulation anatomy and physiology. o Metabolic function of the liver requires a large amount of blood. The liver receives blood from both arterial and venous sources. The hepatic artery is formed by the confluence of superior mesenteric artery and splenic veins and receives blood from the inferior mesenteric, gastric, and cystic veins. It provides oxygenated blood to the liver at the rate of 400 to 500mL/min (about 25% of the cardiac output. The hepatic portal vein receives deoxygenated blood from the inferior and superior mesenteric vein and the splenic vein, deliver 1000 to 1200mL/min of blood to the liver. Hepatic vein is rich in nutrients that have been absorbed from the intestinal track. 3. Discuss the effects of aging on the gastrointestinal tract. o The changes in the GI system that are associated with aging are dependent upon a person’s health status, genetics, and environmental factors. Some changes can begin before the age of 50. As we age, we lose tooth enamel and dentin, which increases the risk for developing cavities. Periodontal disease, gum recession and osteoporosis can cause one to lose teeth. The sense of smell decreases as does the ability to taste secondary to a loss of taste buds. This leads to a reduced appetite in the elderly. Esophageal motility decreases with age and may lead to GERD. Gastric motility, gastric secretions and blood flow decreases with age which leads to an increased risk of injury to the mucosal lining. A decreased production in intrinsic factor is also noted as we age which may lead to B12 deficiency and pernicious anemia. Ileal villi become broader and shorter. Degeneration of the enteric nervous system neurons decreases intestinal absorption, motility, blood flow and impairs nutrient absorption. Nutrients are absorbed more slowly and in lesser amounts. The liver is not able to regenerate as fast in the elderly. Hepatic blood flow decreases with age as does the enzymatic activity both of which decreases drug metabolism. LFTs remain normal in the elderly and an elevation is a sign of a disorder and not a result of aging. The pancreas experiences some age-related fibrosis, fatty acid deposits and atrophy. The beta cells’ function declines as well as we age. Gastrointestinal Bleeds 4. Analyze the etiologies and pathophysiology of osmotic, secretory, and motility related diarrhea. Type of Diarrhea Etiology Pathophysiology Osmotic Osmotic diarrhea is caused by the presence of a nonabsorbable substance in the intestines This is how the laxatives mag citrate, lactulose and MiraLAX work. Excessive ingestion of nonabsorbable sugars can cause this type of diarrhea. Other causes include tube feedings, dumping syndrome, malabsorption, pancreatic enzyme deficiency, bile salt deficiency, small intestine bacterial overgrowth, or celiac disease. This pulls water by osmosis into the intestinal lumen and results in large volume diarrhea